1. Field of the Invention
This invention relates to the manufacture of glass containers on a glass container forming machine of the I.S. (xe2x80x9cindividual sectionxe2x80x9d) type. More particularly, this invention relates to an improvement in the method and apparatus for opening and closing mold carrying arms of such a glass container forming machine.
2. Description of the Related Art
The manufacture of glass containers on a glass container forming machine of the I.S. type is generally described in U.S. Pat. No. 4,427,431 (Mumford et al.), which was assigned to a predecessor of the assignee of the present invention, the disclosure of which is incorporated by reference herein. As is known in the art, an I.S. machine has a multiplicity of side-by-side sections, usually 8, 10 or 12 sections, and glass containers are formed at each machine section in a two-step molding operation. In the first of these steps, a preform of the container, which is often called a parison or a blank, is formed in a first mold at a blank molding station of the I.S. machine section, either by pressing or blowing, and the blank is then transferred by a 180xc2x0 inverting operation in a vertical plane to a second mold of the I.S. machine section, often called a blow mold, for forming into the finished container by blowing. In modern I.S. machines, typically a multiplicity of containers, such as two or three or even four, are simultaneously formed at each section of the I.S. machine, each in the above-described two-step process.
The molds at each section of an I.S. machine, both at the blank molding side and the blow molding side, are split molds each of which is made up of a pair of mold halves. Each mold half has an inner molding surface, and the mold halves in each mold are periodically oscillated into and out of molding contact with each other, the halves of each mold being joined end to end when the mold halves are in contact with each other to form a mold cavity in which the parison or container is formed, as the case may be. One-half of the mold halves at each machine section are carried by a first mold carrying arm, and another one-half of the mold halves at that machine section are carried by a second mold carrying arm, the first and second mold carrying arms being counteroscillated with respect to one another to periodically close and open the molds at that machine section.
As is known, for example, from U.S. Pat. No. 5,803,945 (Grant) and U.S. Pat. No. 5,824,131 (Grant et al.), it is desirable to utilize different speeds during the closing of the mold carrying arms of an I.S. machine, an initial higher speed/lower torque motion during the initial portion of a closing motion, to minimize the time consumed in effecting the closing, and a lower speed/higher torque motion during the final portion of the closing motion, to maximize the clamping forces on the mold halves when closed. However, each of the aforesaid ""945 and ""131 patents requires a pair of drive motors for opening and closing the opposed mold carrying arms at each I.S. machine section, one drive motor for each arm, and the need to provide a pair of drive motors to operate according to the teachings of such references requires substantial space for packaging such motors at an I.S. machine section. Further, the multiple speed operation of each of the drive motors of each of the ""945 and ""131 patents requires complex electronic circuitry (FIG. 16 of each reference), and this is a complexity that appears to introduce reliability problems into the operation of an I.S. machine based on the teachings of these references.
The aforesaid and other problems associated with opening and closing the mold carrying arms of a section of an I.S. machine are overcome by the present invention in which only a single reversible servo motor is employed to power the counteroscillating motion of each of the opposed mold carrying arms at a given I.S. machine section. The servo motor employed in the practice of the present invention operates through a pair of gear drives to provide simultaneous counteroscillating motion to the mold carrying arms, and the available space taken up by the motor and the pair of gear drives is substantially less than that taken up in an installation using a pair of reversible motors, whether of the servo motor type or not. The servo motor utilized in the present invention is provided with dual windings, a first winding for imparting a higher r.p.m./lower torque motion to each of the mold carrying arms for an initial portion of a mold closing motion, and a second winding for imparting a lower r.p.m./higher torque motion during a final portion of the mold closing motion, when higher clamping forces on the mold halves are desired.
Accordingly, it is an object of the present invention to provide an improved apparatus for forming glass containers on a glass container forming machine of the I.S. type. More particularly, it is an object of the present invention to provide an improved apparatus of the aforesaid character for opening and closing mold halves at each I.S. machine section. Even more particularly, it is an object of the present invention to provide a apparatus of the aforesaid character for providing higher speed/lower torque motion to the opposed mold carrying arms at each I.S. machine section during an initial portion of the mold closing cycle, while also providing lower speed/higher torque motion to the mold carrying arms during a final portion of the motion of the mold carrying arms.
For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following brief description thereof, to the detailed description of the preferred embodiment and to the appended claims.